Emissions problem

[Lee Wheatley]

I have a 2000 Ford expedition 5.4. It has 216,000 miles on and runs like a champ! Since last year have not been able to smog because the catalyst monitor will not run. I have changed all eight spark plugs. I have replaced all four catalytic converter. I have replaced all O2 sensors. I have replaced all eight coil packs. I have driven for thousands of Miles highway and city and still the cat monitor will not run. Very frustrated! Would appreciate any help from anybody!

 

[riphip]

Try checking all the vacuum lines if you have not done so. Leaky Vac lines will cause emission problems. Instead of smoke test, just replace them all since they have probably rotted & leaking over the years.
https://www.rockauto.com/en/catalog...8,1362439,exhaust+&+emission,vacuum+hose,5024